Mycobacterial Immune Reconstitution Inflammatory Syndrome in HIV is Associated With Protein-Altering Variants in Hemophagocytic Lymphohistiocytosis-Related Genes

Successful rescue TNF-α blocking for Mycobacterium genavense - Related immune reconstitution inflammatory syndrome: A case report

Immune reconstitution inflammatory syndrome (IRIS) has been reported in immunocompromised patients with disseminated Mycobacterium genavense. Management relies on high-dose corticosteroids. We describe two cases of late-onset corticosteroid-refractory IRIS related to disseminated infection in a HIV-positive patient and a renal transplant patient who had a favorable outcome with a monoclonal TNF-α blocker.

Clonal hematopoiesis in people with advanced HIV and associated inflammatory syndromes

People with HIV (PWH) have a higher age-adjusted mortality due to chronic immune activation and age-related comorbidities. PWH also have higher rates of clonal hematopoiesis (CH) than age-matched non-HIV cohorts; however, risk factors influencing the development and expansion of CH in PWH remain incompletely explored. We investigated the relationship between CH, immune biomarkers, and HIV-associated risk factors (CD4+ and CD8+ T cells, nadir CD4+ count, opportunistic infections [OIs], and immune reconstitution inflammatory syndrome [IRIS]) in a diverse cohort of 197 PWH with median age of 42 years, using a 56-gene panel. Seventy-nine percent had a CD4+ nadir below 200 cells/μL, 58.9% had prior OIs, and 34.5% had a history of IRIS. The prevalence of CH was high (27.4%), even in younger individuals, and CD8+ T cells and nadir CD4+ counts strongly associated with CH after controlling for age. A history of IRIS was associated with CH in a subgroup analysis of patients 35 years of age and older. Inflammatory biomarkers were higher in CH carriers compared with noncarriers, supporting a dysregulated immune state. These findings suggest PWH with low nadir CD4+ and/or inflammatory complications may be at high risk of CH regardless of age and represent a high-risk group that could benefit from risk reduction and potentially targeted immunomodulation.

Tuberculosis-Associated Hemophagocytic Lymphohistiocytosis: Diagnostic Challenges and Determinants of Outcome

Background

Tuberculosis (TB) can induce secondary hemophagocytic lymphohistiocytosis (HLH), a severe inflammatory syndrome with high mortality. We integrated all published reports of adult HIV-negative TB-associated HLH (TB-HLH) to define clinical characteristics, diagnostic strategies, and therapeutic approaches associated with improved survival.

Methods

PubMed, Embase, and Global Index Medicus were searched for eligible records. TB-HLH cases were categorized into (1) patients with a confirmed TB diagnosis receiving antituberculosis treatment while developing HLH and (2) patients presenting with HLH of unknown cause later diagnosed with TB. We used a logistic regression model to define clinical and diagnostic parameters associated with survival.

Results

We identified 115 individual cases, 45 (39.1%) from countries with low TB incidence (<10/100 000 per year). When compared with patients with HLH and known TB (n = 21), patients with HLH of unknown cause (n = 94) more often had extrapulmonary TB (66.7% vs 88.3%), while the opposite was true for pulmonary disease (91.5% vs 59.6%). Overall, Mycobacterium tuberculosis was identified in the bone marrow in 78.4% of patients for whom examination was reported (n = 74). Only 10.5% (4/38) of patients tested had a positive result upon a tuberculin skin test or interferon-γ release assay. In-hospital mortality was 28.1% (27/96) in those treated for TB and 100% (18/18) in those who did not receive antituberculosis treatment (P < .001).

Conclusions

Tuberculosis should be considered a cause of unexplained HLH. TB-HLH is likely underreported, and the diagnostic workup of patients with HLH should include bone marrow investigations for evidence of Mycobacerium tuberculosis. Prompt initiation of antituberculosis treatment likely improves survival in TB-HLH.

Enrichment of Rare Variants of Hemophagocytic Lymphohistiocytosis Genes in Systemic Juvenile Idiopathic Arthritis

Objective

To evaluate whether there is an enrichment of rare variants in familial hemophagocytic lymphohistiocytosis (HLH) genes and systemic juvenile idiopathic arthritis (sJIA) with or without macrophage activation syndrome (MAS).

Methods

Targeted sequencing of HLH genes (LYST, PRF1, RAB27A, STX11, STXBP2, UNC13D) was performed in sJIA subjects from an established cohort. Sequence data from control subjects were obtained in silico (dbGaP:phs000280.v8.p2). Rare variant association testing (RVT) was performed with sequence kernel association test (SKAT) package. Significance was defined as p<0.05 after 100,000 permutations.

Results

Sequencing data from 524 sJIA cases were jointly called and harmonized with exome-derived target data from 3000 controls. Quality control operations produced a set of 481 cases and 2924 ancestrally-matched control subjects. RVT of sJIA cases and controls revealed a significant association with rare protein-altering variants (minor allele frequency [MAF]<0.01) of STXBP2 (p=0.020), and ultra-rare variants (MAF<0.001) of STXBP2 (p=0.007) and UNC13D (p=0.045). A subanalysis of 32 cases with known MAS and 90 without revealed significant association of rare UNC13D variants (p=0.0047). Additionally, sJIA patients more often carried ≥2 HLH variants than did controls (p=0.007), driven largely by digenic combinations involving LYST.

Conclusion

We identified an enrichment of rare HLH variants in sJIA patients compared with healthy controls, driven by STXBP2 and UNC13D. Biallelic variation in HLH genes was associated with sJIA, driven by LYST. Only UNC13D displayed enrichment in patients with MAS. This suggests that HLH variants may contribute to the pathophysiology of sJIA, even without MAS.

Complementary HLH susceptibility factors converge on CD8 T-cell hyperactivation

Hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening hyperinflammatory syndromes. Familial HLH is caused by genetic impairment of granule-mediated cytotoxicity (eg, perforin deficiency). MAS is linked to excess activity of the inflammasome-activated cytokine interleukin-18 (IL-18). Though individually tolerated, mice with dual susceptibility (Prf1⁻/⁻Il18tg; DS) succumb to spontaneous, lethal hyperinflammation. We hypothesized that understanding how these susceptibility factors synergize would uncover key pathomechanisms in the activation, function, and persistence of hyperactivated CD8 T cells. In IL-18 transgenic (Il18tg) mice, IL-18 effects on CD8 T cells drove MAS after a viral (lymphocytic choriomeningitis virus), but not innate (toll like receptor 9), trigger. In vitro, CD8 T cells also required T-cell receptor (TCR) stimulation to fully respond to IL-18. IL-18 induced but perforin deficiency impaired immunoregulatory restimulation-induced cell death (RICD). Paralleling hyperinflammation, DS mice displayed massive postthymic oligoclonal CD8 T-cell hyperactivation in their spleens, livers, and bone marrow as early as 3 weeks. These cells increased proliferation and interferon gamma production, which contrasted with increased expression of receptors and transcription factors associated with exhaustion. Broad-spectrum antibiotics and antiretrovirals failed to ameliorate the disease. Attempting to genetically "fix" TCR antigen-specificity instead demonstrated the persistence of spontaneous HLH and hyperactivation, chiefly on T cells that had evaded TCR fixation. Thus, drivers of HLH may preferentially act on CD8 T cells: IL-18 amplifies activation and demand for RICD, whereas perforin supplies critical immunoregulation. Together, these factors promote a terminal CD8 T-cell activation state, combining features of exhaustion and effector function. Therefore, susceptibility to hyperinflammation may converge on a unique, unrelenting, and antigen-dependent state of CD8 T-cell hyperactivation.

Natural Killer Repertoire Restoration in TB/HIV Co-Infected Individuals Experienced an Immune Reconstitution Syndrome (CAMELIA Trial, ANRS 12153)

IRIS is a common complication in HIV-infected patients treated for tuberculosis (TB) and cART. Our aim was to evaluate NK cell reconstitution in HIV-infected patients with TB-IRIS compared to those without IRIS. 147 HIV-infected patients with TB from the CAMELIA trial were enrolled. HIV+TB+ patients were followed for 32 weeks. The NK cell repertoire was assessed in whole blood at different time points. As CAMELIA has two arms (early and late cART initiation), we analysed them separately. At enrolment, individuals had low CD4 cell counts (27 cells/mm3) and high plasma viral loads (5.76 and 5.50 log/mL for IRIS and non-IRIS individuals, respectively). Thirty-seven people developed IRIS (in the early and late arms). In the early and late arms, we observed similar proportions of total NK and NK cell subsets in TB-IRIS and non-IRIS individuals during follow-up, except for the CD56dimCD16pos (both arms) and CD56dimCD16neg (late arm only) subsets, which were higher in TB-IRIS and non-IRIS individuals, respectively, after cART. Regarding the repertoire and markers of NK cells, significant differences (lower expression of NKp30, NKG2A (CD159a), NKG2D (CD314) were observed in TB-IRIS compared to non-IRIS individuals after the start of cART. In the late arm, some changes (increased expression of CD69, NKG2C, CD158i) were observed in TB-IRIS compared to non-IRIS individuals, but only before cART initiation (during TB treatment). KIR expression by NK cells (CD158a and CD158i) was similar in both groups. CD69 expression by NK cells decreased in all groups. Expression of the NCR repertoire (NKp30, NKp44, NKp46) has similar kinetics in TB-IRIS subjects compared to non-IRIS subjects regardless of the arm analysed. NK cell reconstitution appeared to be better in TB-IRIS subjects. Although NK cell reconstitution is impaired in HIV infection after cART, as previously reported, it does not appear to be affected by the development of IRIS in HIV and TB-infected individuals.